Band structures of Cu2ZnSnS4 and Cu2ZnSnSe4 from many-body methods
Authors: S. Botti, D. Kammerlander, and M.A.L. Marques
Ref.: Appl. Phys. Lett. 98, 241915 (2011)
Abstract: We calculate the band structures of kesterite and stannite Cu2ZnSnS4 and Cu2ZnSnSe4, using a state-of-the-art self-consistent GW approach. Our accurate quasiparticle states allow to discuss: the dependence of the gap on the anion displacement; the key-role of the non-locality of the exchange-correlation potential to obtain good structural parameters; the reliability of less expensive hybrid functional and GGA+U approaches. In particular, we show that even if the band gap is correctly reproduced by hybrid functionals, the band-edge corrections are in disagreement with self-consistent GW results, which has decisive implications for the positioning of the defect levels in the band gap.